}

  public void testColumnKeySet_oneColumn() {
    table = create("a", 1, 'X', "b", 1, 'X');
    assertThat(table.columnKeySet().toString()).isEqualTo("[1]");
  }

  public void testColumnKeySet_oneEntry() {
    table = create("a", 1, 'X');
    assertThat(table.columnKeySet().toString()).isEqualTo("[1]");
  }

  public void testRowEntrySetContains() {
    table =
        sortedTable =